The present disclosure relates to light emitting devices (LEDs).
Light emitting devices (LEDs) are semiconductor devices that convert a current into light. After red LEDs was commercialized, red LEDs and green LEDs have been used as light sources for electronic devices including information communication devices.
For example, a gallium nitride (GaN) semiconductor has a high thermal stability and a wide band gap. The GaN semiconductor can be combined with other elements (e.g., In and Al) to fabricate a semiconductor layer emitting green, blue or white light, and its emitted wavelength is easy to control. Thus, the GaN semiconductor has attracted much attention in the technical fields of high-power electronic devices including LEDs.
According to the related art, not only GaN substrates but also heterogeneous substrates formed of different materials (e.g., silicon, sapphire, and silicon carbide (SiC)) are used to grow GaN epitaxial layers. When GaN-based materials are grown on such heterogeneous substrates, many defects such as threading dislocations (TD) are included in the grown thin layer due to the mismatches between crystal lattice coefficients and thermal expansion coefficients.
Also, according to the related art, a dry etching or wet etching-based isolation process is used to provide the isolation between LED chips. However, the LED may be damaged by plasma or chemicals during the etching-based isolation process, thus degrading the chip reliability.